Influence of grain size on leachability of mine tailings with social indicators assessment of a mining area population
详细信息
- 作者：Drake ; Kenneth David ; Ph.D.
- 学历：Ph.D.
- 年：2010
- 关键词：Grain size ; Leachability ; Mine tailings ; Mining di
- 导师：Hasan, Syed E.
- 毕业院校：University of Missouri
- 专业：Geology, Environmental Health, Public administration
- ISBN：9781124107745
- CBH：3416390
- Country：USA
- 语种：English
- FileSize：5754615
- Pages：177
文摘
The 2,500 square mile Tri-State mining district of southeast Kansas, southwest Missouri, and northeast Oklahoma was a prolific source of lead and zinc from the middle 1800s to 1970. This vast former mining district was an important economic source for the United States during more than a century of historic mineral extraction and is now experiencing the environmental consequences of past mining activities.
Several thousand acres of land are impacted by heavy metals resulting from mining, milling, and smelting the lead and zinc ores; and millions of cubic yards of mine tailings are present at the ground surface. Several environmental cleanups have been conducted, are currently underway, and will continue for several decades into the future.
The grain size of wastes has been shown to be key factor in evaluating risk; however, insufficient work had been conducted to fully explore the relationship between grain diameter and metals leaching potential. Mine tailings were sieved into four standard U.S. sieve size fractions (+4, +16, +50, and -50) and a portion of each fraction was artificially ground to reduce the grain diameter. The original sieved tailings and their size-reduced counterpart samples were then acid leached followed by inductively coupled plasma/mass spectrometry (ICP-MS) analyses of the leachate extracts for lead and zinc.
The chemical test results show levels of lead and zinc were greater in the +50 and larger ground samples as contrasted to the original non-ground samples of the same parent material. The ICP-MS data indicated that levels of lead were approximately 1,663% higher in +4 size ground samples compared to +4 size un-ground samples and the zinc results showed an approximate 71% increase in ground versus un-ground samples for the +4 size tests. The percent differences of lead and zinc ground and un-ground sample concentrations were found to decrease with decreasing grain diameter. The +16 and +50 lead samples showed an approximate 21% and 7% increase, respectively, in ground versus un-ground samples with the respective zinc data showing approximate 30% and 16% increases.
Recent social indicator data for a mining area population in the district were compared to a similar non-mining area population. The results showed that certain health status and socio-economic indicators differed for the mining and comparison populations: the mining area population was found to exhibit higher incidences of elevated blood lead levels, less educational attainment, lower incomes, and higher poverty rates as contrasted to the non-mining comparison population.
Several thousand acres of land are impacted by heavy metals resulting from mining, milling, and smelting the lead and zinc ores; and millions of cubic yards of mine tailings are present at the ground surface. Several environmental cleanups have been conducted, are currently underway, and will continue for several decades into the future.
The grain size of wastes has been shown to be key factor in evaluating risk; however, insufficient work had been conducted to fully explore the relationship between grain diameter and metals leaching potential. Mine tailings were sieved into four standard U.S. sieve size fractions (+4, +16, +50, and -50) and a portion of each fraction was artificially ground to reduce the grain diameter. The original sieved tailings and their size-reduced counterpart samples were then acid leached followed by inductively coupled plasma/mass spectrometry (ICP-MS) analyses of the leachate extracts for lead and zinc.
The chemical test results show levels of lead and zinc were greater in the +50 and larger ground samples as contrasted to the original non-ground samples of the same parent material. The ICP-MS data indicated that levels of lead were approximately 1,663% higher in +4 size ground samples compared to +4 size un-ground samples and the zinc results showed an approximate 71% increase in ground versus un-ground samples for the +4 size tests. The percent differences of lead and zinc ground and un-ground sample concentrations were found to decrease with decreasing grain diameter. The +16 and +50 lead samples showed an approximate 21% and 7% increase, respectively, in ground versus un-ground samples with the respective zinc data showing approximate 30% and 16% increases.
Recent social indicator data for a mining area population in the district were compared to a similar non-mining area population. The results showed that certain health status and socio-economic indicators differed for the mining and comparison populations: the mining area population was found to exhibit higher incidences of elevated blood lead levels, less educational attainment, lower incomes, and higher poverty rates as contrasted to the non-mining comparison population.